Table 1

Clinically most relevant human platelet alloantigen (HPA) systems associated with neonatal alloimmune thrombocytopenia

System	Antigen	Alternative names	Glycoprotein	Nucleotide change	Amino acid change
HPA-1		HPA-1a	Zw^a, pl^A1	GPIIIa	T¹⁹⁶	Leucine³³
HPA-1		HPA-1b	Zw^b, pl^A2		C¹⁹⁶	Proline³³
HPA-2		HPA-2a	Ko^b	GPIbα	C⁵²⁴	Threonine¹⁴⁵
HPA-2		HPA-2b	Ko^a, Sib^a		T⁵²⁴	Methionine¹⁴⁵
HPA-3		HPA-3a	Bak^a, Lek^a	GPIIb	T²⁶²²	Isoleucine⁸⁴³
HPA-3		HPA-3b	Bak^b		G²⁶²²	Serine⁸⁴³
HPA-4^1-150		HPA-4a	Yuk^b, Pen^a	GPIIIa	G⁵²⁶	Arginine¹⁴³
HPA-4^1-150		HPA-4b	Yuk^a, Pen^b		A⁵²⁶	Glutamine¹⁴³
HPA-5		HPA-5a	Br^b, Zav^b	GPIa	G¹⁶⁴⁸	Glutamic acid⁵⁰⁵
HPA-5		HPA-5b	Br^a, Zav^a, Hc^a		A¹⁶⁴⁸	Lysine⁵⁰⁵

↵1-150 Not important in the white population because the mutation has only been detected in populations from the Far East.